1NLF:
reference: Structure of DNA helicase RepA in complex with sulfate at 1.95 A resolution implicates structural changes to an "open" form., Xu H, Strater N, Schroder W, Bottcher C, Ludwig K, Saenger W, Acta Crystallogr D Biol Crystallogr 2003 May;59(Pt 5):815-22. PMID: 12777796

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